Background: The Na sup + channel is voltage gated and characterized by three distinct states: closed, open, and inactivated. To identify the effects of halothane on the cardiac Na sup + current (INa) at various membrane potentials, the effects of 1.2 mm halothane at different holding potentials (VH) on INa were examined in single, enzymatically isolated guinea pig ventricular myocytes.
Methods: The INa was recorded using the whole-cell configuration of the patch-clamp technique. Currents were generated from resting VH s of -110, -80, or -65 mV. State-dependent block was characterized by monitoring frequency dependence, tonic block, and removal of inactivation by veratridine.
Results: Halothane produced significant (P < 0.05) VH -dependent depressions of peak INa (mean +/- SEM): 24.4 +/- 4.1% (VH = -110 mV), 42.1 +/- 3.4% (VH = -80 mV), and 75.2 +/- 1.5% (VH = -65 mV). Recovery from inactivation was significantly increased when cells were held at -80 mV (control, tau = 6.0 +/- 0.3 ms; halothane, tau = 7.1 +/- 0.4 ms), but not at -110 mV. When using a VH of -80 mV, halothane exhibited a use-dependent block, with block of INa increasing from 8.6 +/- 1.4% to 30.7 +/- 3.5% at test pulse rates of 2 and 11 Hz, respectively. Use-dependent inhibition was not apparent at VH of -110 mV. When inactivation of INa was removed by exposure to 100 micro Meter veratridine, no significant difference was observed in the depressant effect of halothane at both VH s: 26.6 +/- 4.5% (VH = -80 mV) and 26.4 +/- 5.6% (VH = -110 mV). 相似文献
Study Objective: To test the hypothesis that the magnitude of the acute hemodynamic response to electroconvulsive therapy (ECT) is related to the duration of the seizure activity in patients receiving different dosages of intravenous (IV) lidocaine.
Patients: 21 ASA physical status I, II, and III patients undergoing four consecutive maintenance ECT treatments for chronic depression.
Interventions: Patients received lidocaine 50 mg, 100 mg, 200 mg IV, or saline prior to induction of anesthesia via a standardized anesthetic technique.
Measurements and Main Results: Noninvasive blood pressure (BP) and heart rate (HR), as well as the duration of motor and electroencephalographic (EEG) seizure, were measured. The duration of motor and EEG seizures (means ± SD) were 37 ± 13 sec and 64 ± 21 sec, 25 ± 11 sec and 52 ± 43 sec, 17 ± 12 sec and 32 ± 17 sec, 1 ± 3 sec and 18 ± 10 sec in the saline, lidocaine 50 mg, 100 mg, 200 mg groups, respectively. Although the duration of seizure activity was decreased in a dose-related fashion after lidocaine pretreatment, the peak increases in BP and HR were similar in the lidocaine and saline treatment groups.
Conclusions: Despite producing dose-related decreases in the duration of both motor and EEG seizure activity, lidocaine failed to attenuate the acute hemodynamic response to ECT. Thus, the acute hemodynamic response to ECT is not related to the duration of seizure activity. 相似文献
The surgical resection rates among parous women with distal ileal and colonic Crohn's disease have been compared with resection rates among distal ileal (n = 197) and colonic (n = 332) Crohn's disease patients. Thirty of 44 parous women with distal ileal Crohn's disease and 28 of 44 with colonic Crohn's disease had achieved their first pregnancy on average 8 years and 6.2 years respectively before the diagnosis of Crohn's disease was established. Resections for each patient were negatively correlated with parity in both groups. (Distal ileal disease (p = 0.034, rs = 0.3207), colonic disease (p = 0.051, rs = -0.2960)). Patients with distal ileal Crohn's disease and a history of pregnancy at diagnosis (n = 30, mean follow up = 15 years) had fewer resections/patient when compared with the published resection group: mean (SD); 1.17 (0.65) v 1.57 (1.05), p = 0.006. Patients with colonic Crohn's disease and a history of pregnancy at diagnosis (n = 28, mean follow up = 16.5 years) had fewer resections/patient when compared with the published resection group: mean (SD); 0.68 (0.77) v 1.05 (0.77), p = 0.019. In summary, patients with distal ileal and colonic Crohn's disease, who had been pregnant in the past subsequently need fewer surgical resections. Pregnancy could influence the natural history of Crohn's disease either by decreasing immune responsiveness or by retarding fibrous stricture formation, which is the commonest indication for surgical intervention. 相似文献
This study of 561 rural North Carolina adolescents examined relationships among race, parental educational level, family structure, parental discipline, family violence exposure, and dating violence experiences. The sample was predominantly female (77%), with 40% black and 58% white. The subjects ranged in age from 15 to 20 years; 80% of the adolescents were 16–18. Dating violence experiences were assessed by a researcher-constructed instrument measuring warning signs of potential violence and actual violent experiences. The results suggested that recognition of abusive relationships is difficult, with many adolescents denying such a relationship but actually reporting numerous abusive events. Sixty percent had experienced violent acts during dating relationships; 24% reported extreme violence (episodes of rape, use of weapons). More than 20% of the adolescents reported family violence and 2.2% reported family sexual abuse. The study suggests new avenues for research in adolescent date violence, and for interventions with high risk groups. 相似文献
After acute brain injury there may be increased intracranial production of
cytokines, with activation of inflammatory cascades. We have sought to
determine if a transcranial cytokine gradient was demonstrable in paired
sera of 32 patients requiring intensive care after acute brain injury. The
difference between concentrations of IL-1 beta, IL-6, IL-8 and TNF alpha in
jugular venous and arterial serum was measured on admission, and at 24, 48
and 96 h after the primary injury. There were no differences in IL-1 beta,
IL-8 or TNF alpha, but median gradients of 6.7 and 11.5 pg ml-1 for IL-6
were demonstrated in the traumatic brain injury (n = 22) and subarachnoid
haemorrhage (n = 10) groups, respectively (normal values in serum < 4.7
pg ml-1; P < 0.001 both groups). This suggests that there is significant
production of IL-6 by intracranial cells after acute brain injury. Therapy
directed towards combatting the negative effects of IL-6 may potentially
benefit patients who have sustained an acute brain injury.
相似文献
Recombinant human stem cell factor (SCF), the ligand for c-kit, has been shown to stimulate increased numbers of hematopoietic progenitor cells of multiple types to circulate in the blood of baboons, but it was not known if the cells stimulated to circulate by SCF contained cells capable of engrafting and rescuing lethally irradiated baboons. Peripheral blood mononuclear cells (PBMNC) were collected by leukapheresis from four untreated control baboons and from three baboons on the 10th or 11th day of treatment with SCF (200 micrograms/kg/d). All animals were transplanted with 1.00 to 1.04 x 10(8)/kg of cryopreserved autologous PBMNC after treatment with a single dose of 1,020 cGy total body irradiation (TBI). Three animals were transplanted with PBMNC that had been collected during SCF treatment, 24 to 38 days after the last dose of SCF. Rapid trilineage engraftment was documented by bone marrow biopsy in all three. The mean time to a total white blood cell count (WBC) > or = 500/microL, WBC > or = 1,000/microL, and an absolute neutrophil count (ANC) > or = 500/microL was 15 +/- 3 (mean +/- SD), 19 +/- 1, and 19 +/- 2 days, respectively. Two animals remain alive with stable engraftment more than 180 and 245 days posttransplant. The third died of sepsis 32 days posttransplant with a hypercellular marrow showing trilineage engraftment. The surviving animals were transfusion independent by 10 and 59 days posttransplant. Four control animals were transplanted with PBMNC collected in the absence of SCF stimulation. One was treated for 11 days with SCF (200 micrograms/kg/d) after PBMNC were collected. This animal was transplanted 25 days after the last dose of SCF. None of the four control animals engrafted and they died 13, 16, 28, and 38 days posttransplant with marrow aplasia. Treatment with SCF stimulates the circulation of cells that engraft and rescue lethally irradiated baboons. The characteristics of the transplantable cells present in the circulation are now amenable to direct study. 相似文献
Background: Endothelium-derived nitric oxide causes vasodilation in part by increasing the dilator activity of other endothelium-derived mediators, including prostacyclin and a K sup +ATP channel-dependent hyperpolarizing factor. Although previous studies have proposed that isoflurane (ISO) depresses endothelium-dependent vasorelaxation by inhibiting endothelium-derived nitric oxide activity, the effects of ISO on the interactions among endothelium-derived dilators have not been characterized. The aim of this study was to determine the mechanisms underlying the inhibitory effect of ISO on endothelium-dependent relaxation in canine pulmonary arteries. Specifically, the goal was to assess the effects of ISO on the individual actions and on the synergistic interactions of these endothelium-derived mediators.
Methods: Canine pulmonary arterial rings were suspended for isometric tension recording. The effects of 1 minimum alveolar concentration ISO (0.4 mM) on vasorelaxation responses to bradykinin, A23187, acetylcholine, cromakalim, and SIN-1 were assessed in phenylephrine-precontracted rings with and without pretreatment with a nitric oxide synthase inhibitor (N sup omega -nitro-L-arginine methyl ester; L-NAME), a cyclooxygenase inhibitor (indomethacin), or a K sup +ATP, channel inhibitor (glybenclamide).
Results: Isofluane attenuated pulmonary vasorelaxation induced by bradykinin, A23187, and cromakalim but had no effect on relaxation induced by acetylcholine or SIN-1. Neither the nitric oxide-mediated nor the prostacyclin-mediated components of relaxation induced by bradykinin and A23187 were altered by ISO. However, ISO abolished the K sup +ATP -mediated component of relaxation and the K sup +ATP -dependent synergistic interaction between nitric oxide and prostacyclin. 相似文献